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 /**
  * Licensed to the Apache Software Foundation (ASF) under one or more
  * contributor license agreements.  See the NOTICE file distributed with
  * this work for additional information regarding copyright ownership.
  * The ASF licenses this file to You under the Apache License, Version 2.0
  * (the "License"); you may not use this file except in compliance with
  * the License.  You may obtain a copy of the License at
  *
  *     http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
 
 package org.apache.mahout.clustering.cdbw;
 
 import java.io.IOException;
 import java.util.List;
 import java.util.Map;
 
 import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.io.IntWritable;
 import org.apache.hadoop.mapreduce.Reducer;
 import org.apache.mahout.clustering.WeightedVectorWritable;
 import org.apache.mahout.math.VectorWritable;
 
 public class CDbwReducer extends Reducer {
 
  private Map> referencePoints;
 
   @Override
   protected void cleanup(Context context) throws IOException, InterruptedException {
    for (Map.Entry> entry : referencePoints.entrySet()) {
       IntWritable iw = new IntWritable(entry.getKey());
       for (VectorWritable vw : entry.getValue()) {
         context.write(iw, vw);
       }
     }
     super.cleanup(context);
   }
 
   @Override
   protected void reduce(IntWritable key, Iterable values, Context context) throws IOException,
       InterruptedException {
     // find the most distant point
     WeightedVectorWritable mdp = null;
     for (WeightedVectorWritable dpw : values) {
       if (mdp == null || mdp.getWeight() < dpw.getWeight()) {
         mdp = new WeightedVectorWritable(dpw.getWeight(), dpw.getVector());
       }
     }
     context.write(new IntWritable(key.get()), new VectorWritable(mdp.getVector()));
   }
 
   @Override
   protected void setup(Context context) throws IOException, InterruptedException {
     super.setup(context);
     Configuration conf = context.getConfiguration();
     try {
      referencePoints = CDbwMapper.getRepresentativePoints(conf);
     } catch (NumberFormatException e) {
       throw new IllegalStateException(e);
     } catch (SecurityException e) {
       throw new IllegalStateException(e);
     } catch (IllegalArgumentException e) {
       throw new IllegalStateException(e);
     }
   }
 
  public void configure(Map> referencePoints) {
    this.referencePoints = referencePoints;
   }
 
 }